(Berkeley, home of the University of California) Berkelium, the eighth member of theactinide transition series, was discovered in December 1949 by Thompson, Ghiorso, andSeaborg, and was the fifth transuranium element synthesized. It was produced by cyclotronbombardment of milligram amounts of 241Am with helium ions at Berkeley, California. Thefirst isotope produced had a mass of 243 and decayed with a half-life of 4.5 hours. Tenisotopes are now known and have been synthesized. The evidence of 249Bk with a half-lifeof 314 days, makes it feasible to isolate berkelium in weighable amounts so that itsproperties can be investigated with macroscopic quantities. One of the first visibleamounts of a pure berkelium compound, berkelium chloride, was produced in 1962. It weighed1 billionth of a gram. Berkelium probably has not yet been prepared in elemental form, butis expected to be a silvery metal, easily soluble in dilute mineral acids, and readilyoxidized by air or oxygen at elevated temperatures to form the oxide. X-ray diffractionmethods have been used to identify various compounds. As with other actinide elements,berkelium tends to accumulate in the skeletal system. Because of its rarity, berkeliumpresently has NO COMMERCIAL OR TECHNOLOGICAL USE.